Kudankulam Nuclear Power Plant and TVS-2M Nuclear Fuel

11th June, 2022 Science and Technology

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Context

Russia has supplied the first batches of more reliable and cost-efficient TVS-2M nuclear fuel to India for the Units 1 & 2 of Kudankulam Nuclear Power Plant (KNPP).

Kudankulam Nuclear Power Plant

Kudankulam Nuclear Power Plant (KKNPP) is the largest nuclear power station in India, situated in Kudankulam in the Tirunelveli district of Tamil Nadu.
Construction on the plant began on 31 March 2002, but faced several delays due to opposition from local fishermen.
KKNPP is scheduled to have six VVER-1000 reactors built in collaboration with Atomstroyexport, the Russian state company and Nuclear Power Corporation of India Limited (NPCIL), with an installed capacity of 6,000 MW of electricity.
The first stage, consisting of power units No. 1 and No. 2, was commissioned in 2013 and 2017, respectively. Power units No. 3,4 and No. 5,6 are the second and third stages of the Kudankulam NPP. Currently, power units 3,4,5,6 are under construction

The new fuel

Newly proposed FAs (Fuel Assembly) called TVS-2M, contain gadolinium-oxide which is mixed with UO2 (by different Gd density and U-235 enrichments), but also the core does not contain BARs (Burnable Absorbers Rods).
With this there will be elongation of the fuel cycle from 12 to 18 months for both VVER-1000 reactors.

NUCLEAR FUEL CYCLE

The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. It consists of steps in the front end, which are the preparation of the fuel, steps in the service period in which the fuel is used during reactor operation, and steps in the back end, which are necessary to safely manage, contain, and either reprocess or dispose of spent nuclear fuel. If spent fuel is not reprocessed, the fuel cycle is referred to as an open fuel cycle (or a once-through fuel cycle); if the spent fuel is reprocessed, it is referred to as a closed fuel cycle.

Advantages of TVS-2M fuel over previous UTVS fuel model

Unlike the UTVS fuel model, which was supplied to Kudankulam NPP earlier, the TVS-2M fuel assemblies have a number of advantages making them more reliable and cost-efficient. Advantages:

Rigidity of a bundle: because of the welded frame, the fuel assemblies in the reactor core retain their geometry, the spacer grids protect fuel rod cladding from fretting wear (preventing from depressurization), and the additional spacer grid makes fuel assemblies more vibration resistant, according to the release.
Secondly, the new fuel has increased uranium capacity -- one TVS-2M assembly contains 7.6 percent more fuel material as compared to UTVS.
The special feature of the Kudankulam fuel in particular is the new generation anti-debris filter ADF-2, protecting bundles from debris damage, which may be caused by small-size intrus objects in the reactor core.
Further, operation in longer fuel cycles also enhances economic efficiency of a plant, as reactors have to undergo stoppage and refuelling less frequently, so the power units produce more electricity.
Due to this, the power plant will need to purchase less fresh fuel, and as a result, will have to deal with smaller amounts of spent nuclear fuel, which also requires expenses.

TVS-2M fuel is efficiently operated in an 18-months fuel cycle at Rostov NPP and Balakovo NPP in Russia, as well as Tianwan NPP in China.
Fuel bundles with ADF-2 anti-debris filter have also shown good results at Rostov NPP.
Besides, all VVER-1000 reactors in Russia operate at higher capacity, 104 percent of the nominal, and this experience is also a matter of interest of nuclear power plant operators abroad.